1. Technical Field
The present disclosure relates generally to wireless communications systems and more particularly relates to a wireless system utilizing millimeter microwave radio frequencies to provide symmetrical, bidirectional broadband telecommunication and multimedia services to remote terminals which distribute the services about the remote terminal location.
2. Description of Related Art
There is an ever-increasing demand for higher bandwidth, multi-service telecommunications to both commercial facilities and residential homes. This demand is driven by the advent of telecommuting, pay-per-view television programming, video-on-demand, and Internet commerce. Services such as these have varied data-types (e.g. voice, broadband multimedia, and video) with widely varying traffic patterns, xe2x80x9cQuality of Service (QoS)xe2x80x9d constraints and bandwidth requirements. As the need for higher bandwidth and more varied services effects a greater number of homes, telecommunication service providers will be tasked with providing the residential home consumer with common access to these services in a fast, cost-effective and easy-to-maintain way.
Fixed wireless technology is gaining popularity as means for transmission of telecommunication services because of its low cost, rapid installation and ease of operation. Connecting two sites with wireless service may largely consist of installing roof top antennas on the top of the sites and connecting the antennas to the accompanying indoor equipment. Physical wires do not have to be connected between the sites, representing a significant advantage over copper or fiber technology. Because deployment of broadband fixed wireless systems does not require civil construction in most instances, it is thus faster and more economical to install than traditional methods of xe2x80x9clast milexe2x80x9d interconnection of offices and homes to a telecommunications network.
Another reason for the growing interest in millimeter microwave radio technology is performance. When broadband wireless links are engineered properly, the links provide a high-bandwidth path for voice, narrow band data, broadband multimedia content and video whose resulting performance can be functionally equivalent to fiber optics. In addition, current technology permits link distances up to five miles.
Providing traditional telecommunication (i.e., telephony) services to residential homes across wireless systems is well known. However, supplying wireless services such as broadband multimedia and video to customers"" homes has more recently begun to emerge and develop. For instance, Multi-point Distribution Systems (MDS) and, more recently, Multi-channel Multi-point Distribution Systems (MMDS) provide wireless television service to households having MDS or MMDS compatible equipment. The initial so-called xe2x80x9cwireless cablexe2x80x9d systems operated within the MDS frequency range of 2150 MHZ to 2162 MHZ. Limited television programming over one or two channels was provided under the MDS frequencies. With the advent of MMDS, operating in a frequency range of 2500 MHZ to 2686 MHZ, a plurality of channels may be simultaneously provided to a microwave antenna located on the rooftop of a customer""s home.
Emerging simultaneously with the development of television programming systems, as described above, has been the need to provide feedback from the customer to the program delivery source such as, for example, pay per view systems. Initially, with respect to wireless cable systems, no such return link existed and the customer was left to rely on making a phone call to the programming source in order to communicate his programming choices. Television set top units were later manufactured which provided standard telephone hookups for sending data back to the programming provider""s billing computer. However, connecting a telephone line to every set top unit is costly.
Instructional Television Fixed Service (ITFS) response frequencies (2686.0625 MHZ to 2689.8125 MHZ) have been considered for use as return link frequencies by the FCC. However, due to the fact that the receive (MMDS) and transmit (ITFS) frequencies are so close to one another, separate receive and transmit antennas were initially required to implement such an approach. This increased the cost and complexity of such a solution.
A system for providing a forward wireless programming path as well as a return over-the-air information/data path which attempts to overcome the above problem is proposed in U.S. Pat. Nos. 5,394,559 and 5,437,052 (both issued to Hemmie et al.). The Hemmie et al. systems provide bidirectional over-the-air transfer of programming and information/data between a common transmission point such as a tower and each of a plurality of remote locations such as consumers"" houses. This is accomplished by utilizing the same microwave antenna at a consumer""s house for receipt of programming and for transmission of data. A bidirectional converter and dual polarity isolated feed system is utilized to receive and to xe2x80x9cdown convertxe2x80x9d the MMDS microwave programming signals and to xe2x80x9cup convertxe2x80x9d and transmit the ITFS response microwave data signals.
However, while such a system provides a bidirectional transfer path, it is to be appreciated that both the forward transmission path and, more severely, the return transmission path, are limited in their service-providing capacity and the system architecture fails to provide compatibility with services other than those which are television programming related.
In the art, point-to-point narrow band, point-to-multi-point narrow band and point-to-point broadband fixed wireless systems are generally known. Point-to-multi-point radio technology is also a known technology that has been generally used for narrow band communications, such as voice. Narrow band systems are typically systems that are capable of generating at or below 1.544 megabits per second of data in a single circuit or channel, whereas broadband systems are capable of generating data rates above 1.544 megabits per seconds per circuit or channel. While narrow band point-to-multi-point systems have been used for voice communications, point-to-multi-point systems have not been generally applied to broadband telecommunications networks.
One example of a typical wireless point-to-point broadband commercial application is the interconnection of multiple servers in a campus local area network (LAN). Another such application is metropolitan wide area networking. In this case, multiple campus LANs within the same city are interconnected via wireless facilities. Dedicated access to inter-exchange carriers (IXCs), Internet Service Providers (ISPs) and other alternate access arrangements are.common point-to-point business applications for wireless links. In the millimeter microwave radio range, cellular and personal communication services (PCS) operators may deploy high availability wireless facilities in their backbone networks to support back haul between antenna sites, base stations and mobile telephone switching offices (MTSO""s). Wireless point-to-point technology is also used to provide mission critical protection channels and other point-to-point alternate routing where extension is required from a fiber network to a location that is not served by fiber. Finally, interconnection with the public switched telephone network (PSTN) for the provision of local dial tone by competitive local exchange carriers (CLECs) utilizing point-to-point wireless technology is becoming increasingly popular.
Referring to FIG. 1, a basic spectrum management problem associated with the use of prior art point-to-point wireless systems in a metropolitan area is shown. Because buildings are close to each other in a metropolitan area, the broadcast of information over wireless links may overlap, making the use of the same channel (1A/1B) in contiguous systems impossible. In FIG. 1, one antenna from one building is transmitting its signal to the antenna of the intended receiver, but a portion of the signal is also being received by the antenna on the adjacent building. Such signal corruption is termed xe2x80x9cco-channel interference.xe2x80x9d
In FIG. 1, a host building 101 containing a switch 102 is connected via four rooftop antennas 103A, 103B, 103C and 103D respectively to remote buildings 104A, 104B, 104C and 104D, each with its own corresponding rooftop antenna. Shown between these buildings is a conceptual representation of the spectrum being utilized by each of these point-to-point wireless systems. As buildings get close together, transmission signals between buildings begin to overlap. To prevent co-channel interference, different channels must be used to connect buildings that are in close proximity. For instance, channel 1A/1B is used for building 104D and channel 2A/2B is used for building 104C. Even though channel 1A/1B partially overlaps the transmission of 2A/2B, the use of different frequencies (channels) by the two systems provides protection from co-channel interference. Thus the antenna of one building may be transmitting a portion of its signal to the wrong receiving antenna, but each system is xe2x80x9ctunedxe2x80x9d to a different frequency and transmission from neighboring systems using other frequencies is ignored.
The frequency management technique shown in FIG. 1 avoids co-channel interference in wireless networks deployed in dense urban areas, however the use of FCC channels to avoid co-channel interference does not maximize the information transport capacity of the licensed spectrum and is therefore inefficient. A solution to this problem is needed.
FIG. 2 illustrates an additional prior art spectrum management problem associated with point-to-point systems. Building 201 connects to building 202 through channel 1. Building 203 connects to building 204 through channel 2. The solid connection lines 205,206 represent the wireless transmission that is intended. However, because the xe2x80x9ctransmit beamxe2x80x9d is about 2 degrees at the source, signals can be received by other systems that are not the intended recipient but happen to be in the range of the transmit beam of the originating system. The dotted line 207 represents such a case, where the system in building 204 unintentionally receives the transmission of the system in building 201. If two distinct frequencies were used, there would be minimal co-channel interference. Once again, frequency management in point-to-point wireless networks requires the use of multiple channels to avoid interference rather than allowing the spectrum to be used to drive incremental bandwidth.
Antenna tower space is expensive and in many cases there are restrictions on the number, size and position of antennas deployed on a tower. Because point-to-point systems use separate antennas for each wireless connection, space quickly becomes a limiting factor on hub buildings or hub towers. As the number of point-to-point systems located on a building increases, not only do spectrum management considerations limit the number of systems which can be deployed, but the physical space available for each antenna on the hub buildings or hub tower also constrains the number of systems. Thus, a solution is required which permits the expansion of wireless network capacity, and thus the number of users, without a corresponding increase in the number of antennas.
Point-to-point systems provide users with what is called a full period connection. Full period connections are xe2x80x9calways onxe2x80x9d (connected and active), awaiting the transport of information. Full period wireless connections utilize dedicated spectrum, which, once assigned, is unavailable to other users. Point-to-point wireless systems are therefore appropriate for applications involving continuous or lengthy transmissions. Point-to-point systems do not efficiently support variable bit rate or xe2x80x9cburstyxe2x80x9d data services where the requirement for bandwidth is not constant but rather variable. Bandwidth utilized by point-to-point systems for variable bit rate applications is wasted, as each system utilizes the allocated channel on a full time xe2x80x9calways onxe2x80x9d basis regardless of the amount of information or the duration of transmissions on the link. A solution is required to more efficiently utilize spectrum for xe2x80x9cburstyxe2x80x9d data services like LAN to LAN data transmission.
It would therefore be advantageous to provide a wireless system utilizing millimeter microwave radio frequencies to provide symmetrical, bidirectional broadband telecommunication and multimedia services between a hub radio and remote terminal. To enable such a system, a cost-effective remote terminal is required to transfer data with the hub radio and distribute multi-service broadband telecommunication and multimedia services at the remote terminal location.
It therefore is an object to provide a wireless system utilizing millimeter microwave radio frequencies to provide symmetrical, bidirectional broadband telecommunication and multimedia services to remote terminals.
It is another object to provide a millimeter microwave computer-controlled radio system at the remote terminal location.
It is yet another object to provide a millimeter microwave computer-controlled radio system at the remote terminal location taking the form of a circuit board installed in a personal computer which receives and transmits signals within the millimeter microwave frequency range and distributes the broadband telecommunication and multimedia services at the remote terminal location.
It is yet another object to provide a millimeter microwave computer-controlled radio system at the remote terminal location taking the form of a stand-alone system which receives and transmits signals within the millimeter microwave frequency range and distributes the broadband telecommunication and multimedia services at the remote terminal location.
It is yet another object to provide symmetrical, high bandwidth bidirectional telecommunication and multimedia services between a hub radio and remote terminals.
It is another object to provide a method of eliminating co-channel interference between remote subscribers utilizing the same hub radio.
It is another object to increase the effective range of customer facilities using a broadband wireless link.
It is another object to provide multiple access or point to multipont access between a hub radio and a plurality of remote terminals.
It is still another object to form a linkage between the single radio hub and a remote customer terminal.
In accordance with one form of the present system a multi-service subscriber radio unit includes an antenna and a transceiver which is operatively coupled to the antenna. The radio unit further includes a modem which is interposed between the transceiver and a packet control unit. The packet control unit provides multi-service packetized data for transmission (up-link) to the modem and receives multi-service packetized data from the modem (down-link). The packet control unit extracts service specific packetized data from the received multi-service packetized data and also generates the transmit multi-service packetized data from a plurality of service specific data from customer premise equipment. A plurality of service interface units are included which provide a suitable electrical interface between the customer premise equipment and the radio unit. A distribution control unit is interposed between the packet control unit and the plurality of service interface units. The distribution control unit directs service specific data to and from the service interface units.
Preferably, the packetized data takes the form of Asynchronous Transfer Mode protocol data. In a further preferred embodiment, the plurality of service interface units include at least one of an Internet service interface, a television set top box interface, and a telephony interface.
The transceiver, modem, packet control unit, distribution control unit and plurality of service interface units can be as an integrated printed circuit board for insertion into a standard computer interface slot. Alternatively, a dedicated controller can be included and the transceiver, modem, packet control unit, distribution control unit, plurality of service interface units and dedicated controller can be formed as a stand-alone unit. In yet another alternate embodiment, the antenna and transceiver are integrated as an outdoor unit and the modem, packet control unit, distribution control unit and plurality of service interface units are integrated as an indoor unit. The indoor unit can be formed as a standard computer card or as a stand alone unit with a dedicated controller. In either case, the outdoor unit and indoor unit are coupled by a high bandwidth conduit, which may be wireless, copper or fiber.
In the above embodiments, it is preferable that the transceiver supports a multiple access protocol. One such protocol is time division multiplexing.
In another embodiment, a communications system is formed which provides access between remote customer premise equipment and service providers. The system includes a hub site which is coupled to a plurality of service providers and exchanges packetized service data therewith. The hub site merges the packetized service data into multi-service data which is provided to a hub radio for establishing bidirectional multi-service wireless data communications in a coverage sector. The system also includes a remote subscriber unit. The remote subscriber unit includes a subscriber radio for exchanging multi-service data with the hub radio. The remote subscriber unit extracts a plurality of service specific signals from the multi service data and directs the service specific signals to a plurality of customer premise equipment. The remote subscriber unit also receives a plurality of service specific signals from the customer premise equipment and transmits a multi-service signal to the hub radio, whereby bidirectional multi-service communication is provided.
These and other objects, features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.